This invention relates generally to surgical instruments and, more particularly, to a device for percutaneous incisional breast biopsy.
The early diagnosis of breast cancer through the use of mammography is very important for reducing the morbidity associated with breast cancer. Early diagnosis enables a physician to treat the breast cancer at a more manageable stage of development. Mammography is capable of detecting very small abnormalities in breast tissue. However, mammography usually cannot differentiate between malignant and benign lesions in the breast. Definitive determination of the status of a lesion often requires a histological examination of the suspect tissue.
One method for obtaining a tissue sample for histological examination is through a biopsy of part or all of the suspect tissue. There are a number of devices and methods for performing a biopsy of the breast. Generally, the procedure requires first placing a localization needle within or near the lesion. A guide wire contained within the localization needle is then deployed. The guide wire usually includes hooks that anchor one end of the guide wire in breast tissue near the lesion. Then a biopsy device that includes a cannula and a stylet located within the cannula is inserted over the localization needle and guide wire. The device is inserted through a small incision in the breast tissue near the entry point of the localization needle. The stylet bluntly separates breast tissue as the device is inserted over the guide wire toward the lesion. Advancement of the device is stopped once the tip of the stylet is within or near the lesion. Then, the cannula, which has a cutting surface at a leading edge, is advanced over the stylet and into the tissue thereby cutting a core of tissue. The cutting surface is advanced to a point beyond the end of the guide wire. Then, a second cutting surface, typically a wire garrote, is activated to perform a cut transverse to the core and to a longitudinal axis of the cannula creating a tissue sample. Then the needle, guide wire, and device are retracted from the breast with the tissue sample. The tissue sample is then histologically examined to determine whether the suspect tissue is malignant or benign.
The current biopsy devices have a number of disadvantages including that the device, localization needle, and guide wire are not manufactured as a single unit; also the devices generally do not have a means for insuring that the garrote wire is located past the end of the guide wire prior to deployment of the garrote. To determine whether the garrote is located past the end of the guide wire with a typical biopsy device, a radiographic check is required. Finally, the typical blunt stylet requires substantial force to insert and may cause trauma to the healthy tissue as it passes to the biopsy site.
Therefore, it is desirable to provide a biopsy device manufactured as an integrated unit having a localization needle and a guide wire. Additionally, it is desirable to provide a biopsy device having features to insure that the garrote wire is not deployed until it is past the end of the guide wire. It is also desirable to provide a stylet with cutting members to cleanly transect and separate breast tissue and minimize the damage to healthy tissue.
The present invention overcomes the problems with previous biopsy devices by providing a biopsy device which is manufactured with an integral localization needle and guide wire. In addition, the invention includes structure to insure that the garrote wire is not deployed until the garrote wire is beyond the end of the guide wire. Further, the stylet is provided a blade which transects tissue as the device is inserted to the biopsy site.
According to one aspect of the present invention, the device includes a cannula having a shaft with a cutting surface on one end of the shaft and the other end of the shaft in engagement with a drive assembly. Adjacent to the cutting surface of the cannula is a second cutting mechanism for making a cut transverse to a cut made by the shaft cutting surface. Located within the cannula shaft is a stylet. The stylet has a tip portion with a blade for transecting and separating tissue and a central chamber for permitting a localization needle to pass through the length of the stylet. The localization needle has an interior chamber permitting passage of a guide wire through the length of the localization needle. The device also includes a lock feature for preventing deployment of the second cutting mechanism until it is past the end of the guide wire.
According to a further aspect of the present invention, a method of removing suspect breast tissue with a breast biopsy device includes the steps of inserting a localization needle into tissue, advancing a hooked guide wire out of a distal end of the localization needle to anchor the biopsy device in the tissue in or near a lesion, advancing a stylet and cannula over the localization needle until the stylet is adjacent the lesion, advancing a cannula shaft cutting surface to cut a core of tissue, unlocking a trigger of a garrote when a cutting plane of the garrote has been advanced past a distal end of the guide wire, and moving the trigger to activate the garrote and make a cut transverse to the direction of advancement of the cannula shaft.